Safety valve



Sept. 4, 1934. G. ACKERMANN SAFETY VALVE Original Filed Oct. 30, 1930Patented Sept. 4, 1934 UNITE-D STATES SAFETY VALVE Gottlieb Ackermann,Berlin, Germany Original application October 30, 1930, Serial No.

492,320. Divided and this application September 28, 1931, Serial No.565,632. In Great Britain September 16, 1930 1 Claim.

This invention relates to safety valves for steam boilers and otherpressure medium containers of the kind in which a back pressure chamberin the valve casing is on the opening of the valve iilled with thepressure medium, which in the closing movement ofthe valve aids theclosing force of the spring or other closing means, and it relatesparticularly to safety valves in which the opening movement takes placein successive stages, the valves being so arranged that on the maximumpressure permissible for the boiler being exceeded they open to a deniteheight, and when in spite of the raised safety valve the boiler pressurestill increases, they open still further, that is, open a larger outletarea.

An object of the invention is to provide a valve of this kind in whichthere is a continuously open outlet and a throttling device co-operatingwith the said outlet and controlled by the valve to damp or check themovement of the valve. The throttling of the outlet is increased on theclosing stroke so that the increasing pressure in the chamber overcomeswith certainty the resistance to the closing stroke which is caused bythe steam cushion forming under the lower surface of the valve, the twoiniiuences, viz: the steam cushion and the pressure in the chamber heremaintaining practically an equilibrium, so that a forcible applicationof the valve on its seat cannot take place. Other objects and advantagesof the invention will be understood from the following description readin conjunction with the accompanying drawing, which illustrates incentral vertical section a safety valve exemplifying the invention.

The valve casing 1 is connected by the socket 2 with the steam boiler orother pressure medium container, 3 indicating the outlet leading to theatmosphere. The valve body 4 has a bell-shaped guide projection 5 whichextends into a sleeve 6 of the valve casing. Between the guideprojection 5 and the sleeve 6 a narrow gap 24 may be provided which isadapted to serve both as an inlet and an outlet oi the back pressurechamber '7. Narrow bores 8 also serve as inlets to this chamber '7. Thesleeve 9 forms the outlet, and has a conical bore widening upwardly, inwhich bore the valve spindle 11 has an enlargement 10. 12 indicates aspring plate, and 13 the valve spring. The valve has an annularsupplementary under surface 14, under which a steam cushion forms whenthe valve rises. The ring 15 is provided with an upward extension 16.

When the permissible maximum pressure in the boiler is exceeded, thevalve 4 lifts, then steam ows through the holes 8, or through the gap24, or through both into the back pressure chamber 7. When the valve 4has reached a level Vcorresponding with a certain definite pressure, ifthe pressure continues to rise, then in consequence of the shape of theinner outline of the extension 16, no widening of the outow area takesplace, and the valve must therefore lift further until its inclinedlower surface rises into a position opposite the widened outlet part atthe top of the ring 16, when the outlet area is larger, and thus agraduated opening of the valve is obtained. In order to be able to varyat will the difference of pressure which is necessary for the furthermovement of the valve from the rst to the second raised position asabove mentioned, auxiliary outlet holes 17 may be made in the extension16, which holes 17 may be more or less throttled by means of upwardadjustment of the ring 18, which is screw threaded on the ring 15.

When the boiler pressure has fallen so far that the expansive force ofthe spring 13, combined with the pressure in the chamber 7, can forceback the valve 4 onto its seat, the outlet from the chamber 7 throughthe sleeve 9 is throttled more and more by the downward movement of theenlargment 10 on the valve spindle ll, the pressure in the chamber 'lrises, and combines with the decreasing action of the spring 13 toeffect the overcoming of the back pressure of the steam cushion actingfrom underneath on the surface 14, so that the valve is closed without aheavy shock, in spite of the increased pressure in the chamber '7. Y

This application is a division of application, Serial No. 492,320, filedOctober 30, 1930, which has since matured into Patent No. 1,952,646.

What I claim and desire to secure by Letters Patent of the United Statesis:-

In a safety valve apparatus, a casing comprising a valve seat and anexhaust port, a movable valve body, means tending to press said body'onsaid seat, said casing and body conjointly forming a back pressurechamber of variable capacity, means to admit the pressure medium to saidchamber, an outlet sleeve on said casing to provide communicationbetween said chamber and the atmosphere, said sleeve having a taperedopening widening outwardly and provided at the inwardly reduced endthereof with a cylindrical extension, and a stem movable with said valvebody and provided with an annular throttling enlargement intermediateits ends, said enlargement being positioned within and adjacent theinner reduced end of the sleeve and spaced from the said sleeve toprovide a passage around the enlargement when the valve is seated andmovable toward the outer end of the sleeve when the valve is unseated toincrease the passage progressively with the entire opening stroke ofsaid valve body. Y

GOTTLIEB ACKERMANN.

